I received my Moto G 4G (XT1039, Android 4.4.3) from Tesco yesterday. I put in a 32gb Sandisk Ultra sdcard that used to live in my Sony Ericsson SK17i, and it said the card was damaged (reformat?). I let it reformat, thinking the phone would do it best, and it worked - I could store stuff on the card...
...until this morning, when I noticed that some of the games I'd downloaded last night had vanished from the menu. Then I spotted the 'Blank SD card' notification.
I tried a restart, but it's still supposedly blank. It's definitely not, as I can read the contents using my SK17i.